I am quite at early stages with analog electronics. About the schematic in post #1, could someone please explain me how the two input operational amplifiers work or where I could find such informations please?
I can't understand how they are configured. Are they making from one input signal two opposite signals to drive the amplifier?
I can't understand how they are configured. Are they making from one input signal two opposite signals to drive the amplifier?
Opamp U2A forms a basic balanced to unbalanced converter. The audio appears at the opamp output. U2B is a simple inverting configuration that takes the output of U2A as its input.
The gain of U2B is -1 as configured due to equality of R8 and R11.
So we have two audio signals, one being 180 degrees different in phase to the other.
The inverting stage is classic opamp theory.
There are lots of resources on the web if you look for 'Opamp Theory'
http://www.ti.com/lit/an/sboa092b/sboa092b.pdf
https://www.analog.com/media/en/training-seminars/design-handbooks/Basic-Linear-Design/Chapter1.pdf
This might be more readable. There is a part 2 and 3 as well:
Audio Designs With Opamps
The gain of U2B is -1 as configured due to equality of R8 and R11.
So we have two audio signals, one being 180 degrees different in phase to the other.
The inverting stage is classic opamp theory.
There are lots of resources on the web if you look for 'Opamp Theory'
http://www.ti.com/lit/an/sboa092b/sboa092b.pdf
https://www.analog.com/media/en/training-seminars/design-handbooks/Basic-Linear-Design/Chapter1.pdf
This might be more readable. There is a part 2 and 3 as well:
Audio Designs With Opamps
Thank you.
I was not aware of the existence of balanced signals and didn't know were to start looking.
Basically if I have only unbalanced lines I would need only the inverting amplifier to feed the differential input of the amplifier, right?
I was not aware of the existence of balanced signals and didn't know were to start looking.
Basically if I have only unbalanced lines I would need only the inverting amplifier to feed the differential input of the amplifier, right?
In theory yes, however the first stage provides a defined input and also has voltage gain as configured.
Great work, almost just what I needed🙂 I would like to modify the input OPAMPs power supplies to have them run on +-5V and eliminate capacitors in the signal path. Can I have the CAD files?
Is the circuit of the PFFB (post filter feedback) amplifier you made a circuit diagram in the attached file?